Soluble rosin salts are surface active materials which generally makes them useful as emulsifiers. The sodium salts of rosin were used to stabilize the first dispersed rosin sizing agents that were developed (see, for example, Davison, U.S. Pat. No. 3,565,755). Unfortunately, the stability of these products was not great. They were shear sensitive and the particles settled over time; sediment that collected at the bottom of tanks was difficult to remove.
Not previously evaluated are the alkanolamine salts of rosin. Alkanolamine salts of fatty acids are known to be emulsifying agents. As, for example, in the Kirk-Othmer Encyclopedia of Chemical Technology. “Alkanolamines and long-chain fatty acids react at room temperature to give neutral alkanolamine soaps, which are waxy, noncrystalline materials with widespread commercial applications as emulsifiers.” Analogous statements about the alkanolamine salts of rosin are not apparent in the literature. German Temporary Patent #1,131,348 (Jun. 14, 1962) makes mention of dispersions of “resin with a certain percentage of rosin soap” that contain “auxiliary emulsifiers, stabilzers, such as stearates, triethanolamine, casein, waxes, fillers, such as kaolin, and other additives,” but the identities of the stabilizers are unclear from this reference. Alkanolamines are not among the “suitable alkaline materials” listed by Davison.